OPERATING MANUAL
C-4
21833-3.4
NORMARC 7013
INSTRUMENT LANDING SYSTEM
Maintenance Procedures ©1999 Navia Aviation AS
1. A portable ILS receiver (PIR).
2. BIRD wattmeter.
3. Digital voltmeter (dvm).
4. The FA-9438 modulation meter.
NOTE:
Chapter 1, Paragraph 1-2b, Test Equipment, discusses external test equipment and BITE,
and their proper use in the NAS. Particular attention must be paid to the proper use and main-
tenance of test equipment to ensure accurate evaluations of equipment operation.
d. Conditions.
A facility shutdown is required for this check.
e. Detailed Procedure.
1. Preliminary actions.
(a) Refer to Navia Aviation Form “Localizer Monitor Reference Data” for the applicable refer-
ence values.
(b) Verify, as accurately as possible, that modulation is 20 percent for each tone. (PIR con-
nected to CSB COU test connector on facility front). The facility must be properly phased.
(c) Bypass the monitor to prevent shutdown.
2. Width alarms.
(a) Connect the dvm to the transmitter SBO test connector.. This voltage represents the nomi-
nal transmitter SBO power in front of the SBO step attenuator. Measure the dc voltage, note
the transmitter SBO attenuator value and record in Table “Localizer Monitor Reference Data”.
Compare the values to the reference values. If found outside the tolerance ivestigation should
be carried out.
(b) Decrease the sideband power (increase the SBO attenuator value) until the monitor is in
alarm. Confirm that this attenuator value is not greater than the flight checked reference value.
Record this SBO attenuator value. If this SBO attenuator value has been exceeded, corrective
action should be taken.
(c) Measure and record the width monitor DDM in Table “Localizer Monitor Reference Data”.
The width DDM is availible in the PMDT Monitor 1 window. Note that no tolerance exists on
this entry. It is used to detect trends.
(d) Increase the sideband power (decrease the SBO attenuator value) until the monitor is in
alarm. Confirm that this attenuator value is not less than the flight checked reference value.
Record this SBO attenuator value. If this SBO attenuator value has been exceeded, corrective
action should be taken.
(e) Measure and record the width monitor DDM in “Localizer Monitor Reference Data”. The
width DDM is availible in the PMDT Monitor 1 window. Note that no tolerance exists on this
entry. It is used to detect trends.
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